Bug 1345763 part.1 Implement AsTextEditor() in EditorBase and its subclasses and replace casts with it r=smaug

MozReview-Commit-ID: 3ZyBefyc45N

--HG--
extra : rebase_source : 0af0607849b9a19859b73b327887c895ae08036b

editor/libeditor/EditorBase.h

@@ -119,6 +119,7 @@ class JoinNodeTransaction;
 class RemoveStyleSheetTransaction;
 class SplitNodeTransaction;
 class TextComposition;
+class TextEditor;
 struct EditorDOMPoint;
 
 namespace dom {
@@ -164,6 +165,9 @@ public:
    */
   EditorBase();
 
+  virtual TextEditor* AsTextEditor() = 0;
+  virtual const TextEditor* AsTextEditor() const = 0;
+
 protected:
   /**
    * The default destructor. This should suffice. Should this be pure virtual

editor/libeditor/HTMLEditor.cpp

@@ -510,7 +510,7 @@ HTMLEditor::InitRules()
     // instantiate the rules for the html editor
     mRules = new HTMLEditRules();
   }
-  return mRules->Init(static_cast<TextEditor*>(this));
+  return mRules->Init(this);
 }
 
 NS_IMETHODIMP

editor/libeditor/TextEditor.h

@@ -56,6 +56,9 @@ public:
 
   TextEditor();
 
+  virtual TextEditor* AsTextEditor() override { return this; }
+  virtual const TextEditor* AsTextEditor() const override { return this; }
+
   // nsIPlaintextEditor methods
   NS_DECL_NSIPLAINTEXTEDITOR